


Quintessential Lessons

by snasational



Series: Classic Vs The Multiverse [5]
Category: Undertale (Video Game)
Genre: Errortale Sans (Undertale), M/M, Mutual Masturbation, Slight Voyeurism
Language: English
Status: Completed
Published: 2021-01-24
Updated: 2021-01-24
Packaged: 2021-03-16 09:28:20
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,617
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28954218
Author URL: https://archiveofourown.org/users/snasational/pseuds/snasational
Summary: “Okay. Cool. Leave.”Sans chuckles. Error’s fingers twitch.
Relationships: Sans/Sans (Undertale)
Series: Classic Vs The Multiverse [5]
Series URL: https://archiveofourown.org/series/2065212
Comments: 6
Kudos: 113





	Quintessential Lessons

**Author's Note:**

  * For [TDoompoet](https://archiveofourown.org/users/TDoompoet/gifts).



> My rendition of Error remembers being Sans, but he doesn't remember being Geno. 
> 
> Dedicating this one to TDoompoet, who won the raffle and requested this!

“Cozy place you have here.” 

Error slumps into his beanbag, exhaustion written clear as day on his face. Sans sits in front of him, legs crossed and hands folded in his lap. Error has quite frankly had enough of today, and being faced with Classic has done his mental well being no good. 

“How did you even get here?” His part of the anti-void is near impossible to reach unless you know where you’re going, or if Error directly invites someone. Knowing that Sans managed to waltz in here gives him a headache. What an annoyance. 

“I dunno.” Sans shrugs. He looks bored. Is that truly how Error used to be? Nonchalant and uncaring? What an infuriating mix. It’s a wonder this guy didn’t have more enemies. “That colorful me had something to do with it, I think.”

Ink or Fresh. Either way, abominations like them live only to see Error suffer. They’re well aware of his feelings towards the original, and yet they pull a prank like dragging him to what is supposed to be Error’s safe place. He’ll repay them kindly. Perhaps get Nightmare and his gang of misfits aboard his plan? Much as he hates dealing with anomalies, partnerships can be mutually beneficial. 

“Okay. Cool. Leave.” 

Sans chuckles. Error’s fingers twitch. 

“Heh. You’re a friendly guy, aren’t you?” A callousness sharpens the edge of Sans’ grin. 

Right, how could Error forget? Beneath those layers of nonchalance is a malicious being fueled by spite and bitterness. It seems like eons ago, but at one point Error stood in his shoes. Although he doesn’t remember what led to him being Error, he does remember the before. 

Pain. Insanity. When are the resets going to end? When will the kid stop? How many times must he see his brother and friends die? Is Gaster laughing at him from the void? Error closes his eyes. He doesn’t have a brother. Gaster does not exist. Error is not Classic, dwelling on a past that's long since been erased does him no good. 

“My friendliness is none of your business.” He tells him. “None of the multiverse is your concern. The fact that they even allowed you to roam in it is astounding.” 

Sans tilts his head. “Why isn’t it my business?”

Error opens his eyes to level him with a nasty glare. “You’re the original. The main universe. You are not an abomination, therefore you should stay in your own timeline. Leaving it risks you getting... _ tainted  _ by other universes.” 

“Wow. So you think that all of the other universes are abominations?” Sans asks innocently. Error doesn’t trust it. 

“Yes.”

“Then that makes you one too, doesn’t it?” 

Error stares at him. Something akin to horror grips at the skeleton. Him? One of the very anomalies he’s spent his entire life hunting down? It’s laughable. He is nothing like them. “No. I have a purpose and they don’t.” 

“And that purpose is?”

“To destroy them.”

Sans pauses. Error takes glee in the fact that he managed to make Sans second guess his next words. Life isn’t so easy when there’s the promise of a reset, is it? There is no script to work off of, and each conversation brings forth a new unknown situation where you don’t know the person’s next words. How lost he must feel. 

Error smirks. 

“Hm. You’re even edgier than edgy me.” 

Error chokes back an offended noise. “Are you comparing me to an  _ Underfell  _ Sans?” 

“I don’t know what ‘Underfell’ is, buddy. But I guess? We’re both talking about the sweaty guy with the sharp teeth and expensive jewelry, right?” 

So he met the original Underfell Sans. Regardless, even if its worlds better than the deranged slut that insists on wearing a collar, the comparison isn’t flattering. 

“I am nothing like him!” Error hisses.

“Well, appearance wise you look like me if I was a computer program that got infected with a ton of viruses. But personality wise? Man oh man, the two of you sure do like your violence.” Sans tsks and shakes his skull chidingly. A mannerism picked up from Toriel, no doubt. 

At the thought of Toriel, his soul gives a painful twinge. Late nights spent by a door, laughter shared between two lonely beings. Her touch was particularly nice. Her paws were large and her fur was soft. She was...nice. Being around her was nice. And even when his sole purpose in life is to destroy, he finds himself feeling strange when he has to destroy any variation of her. 

  
  


“First off, his approach is brutish. No tact whatsoever. Second off, he was one of the firsts anomalies to appear. His existence is an affront to everything I try and achieve.” 

Sans hums and rests his chin in the palm of his hand. “What good does destroying anomalies do? I mean, they don’t affect my existence and they don’t affect yours either. What’s wrong with simply allowing them to live? To me, it seems like you’re taking unnecessary lives.” 

“Don’t speak on things you know nothing about.” Error growls. Anger seeps into his marrow at Sans’ words, full of judgement and contempt. “There is no reason for them to exist. Only one universe should be allowed, the rest are meaningless and detestable. It is my job to tear them down.”

“I guess I’m the lucky winner, huh? My world gets to live because I’m the original and the rest get to burn. That hardly seems fair to me.” 

Oh. He gets it now. Ink set this all up in hopes that Sans’ philosophical bullshit manages to change his mind. “You couldn’t change Chara’s mind so what makes you think you can change mine?” 

Sans’ expression doesn’t change. It never does, and it took years of practice to get it like that. But Error can feel the surge of anger roll off him in waves. The kids are always going to be a sore spot for him, and Error is going to exploit it to the best of his abilities. You’d think by now Sans would know not to go poking bears. 

“You’re right.” Sans says instead of some virtue signalling bullshit. Error doesn’t expect that. He shifts in his seat, suddenly uncomfortable. He was relying on Sans’ predictability, but the guy totally managed to pull the rug from underneath him. 

“Of course I am.” 

Sans gives a shrug and pulls out a ketchup packet. 

“Yeah. I mean, you’re basically just another Chara anyways. What, with the whole genocide thing. Killing innocent people, gaining LOVE through their suffering. I don’t have to check you to know how high your LV is, just by looking at you I can tell you’re a creature past reasoning with. Just like them. Fact is, that colorful guy looked so hopeful that I had to at least try.” 

If Sans were anyone else, he would’ve attacked him. Nobody would’ve gotten away with speaking to him like that. Instead, he seethes. “What I do is not the same as what Chara does.”

“Oh? And what is the difference?” He tears open a packet and squirts it directly into his mouth. Error cringes at the gross display. To think that at one point they were the same person...deplorable. 

“It...It just isn’t the same.” Error insists. “I’m getting tired of you. Don’t you have anything better to do?” 

Sans shakes his head. “No. I can’t shortcut here either, so I guess that means you’re stuck with me until the other guy shows up again.” 

Error rolls his eyelights. “Yeah, no. Not happening. You’re going home. I can teleport universes.” 

“Oh? Well in that case, take me home.” He scooches closer to error and raises his hand to touch him, but Error flinches away before he can make the contact. Sans’ hand freezes midair. It’s too late to come up with any excuse as to why he flinched, and Error doubts Sans would by any lie. 

“Don’t say a fucking thing.” Error warns. He’s absolutely mortified by his impulsive response and if he could, he would strangle himself. 

“...I wasn’t going to.” Error doesn’t know if he believes him or not. “Um. You’re...glitching?” 

Warning signs flood his vision and he gets that fuzzy feeling that comes right before a crash. Sans didn’t actually touch you, he tries to remind himself. Why are you acting like this? “You are such a nuisance.” He spits out in a staticy voice. Some of the words repeat against his will, exactly like a virus infected computer would. 

Error hates Sans for making that comparison earlier. He knows it’s true even if no one else has ever outright said it before. He doesn’t understand why Classic has the balls to do and say things other Sanses would never even think of. What makes him so special, so untouchable aside from the fact that he happens to be from the original timeline? 

Error despises him. He wishes he could kill him. He wishes he could destroy his entire timeline and force him to watch as all of his beloved friends and family are taken away. It would certainly wipe that know it all grin from the bastard’s face. He wants to see it replaced with devastation. He wants to be the reason why Sans feels misery.

But…

Why?

Why does he wish all of these cruel things? Is it because Sans is the one person who’s truly safe from Error’s righteous anger? 

“...and then the fluffy bunny peeked around the corner, and…”

Error blinks. He can’t see anything past the swarm of text blocking his vision. “Are you reading Peek-a-Boo With Fluffy Bunny right now?” He asks incredulously.

“More like reciting.”

Slowly, his vision clears. Sans has backed up again, giving Error plenty of room to breathe. “...Why?” 

“I dunno. Reading it makes me feel better, I guess.” 

Right. Error can still recall every word, too. He can remember the weight of Papyrus in his arms, the feeling of brick against his back and the numbness of his mouth as he repeated the story over and over again. He shakes the unwanted memories from his head. In the end, they’re things that never happened and they only hold him back from his goal. 

“Oh.”

“Mhm.” They lapse into an uncomfortable silence. Error only has episodes in front of a certain set of people, having anyone outside of that group witness him crash is embarrassing. His face begins to heat against his will, the black bone being colored deep blue. Sans studies his face and Error pretends that he isn't even there.    
  


“...I’m turning on the T.V.” 

Sans blinks when a boxed television appears next to him. “Out of any T.V you could have summoned, you choose one that’s from the 60s?” 

“70s, actually.” Error interrupts. “Are you going to keep saying dumb things or are you going to shut the hell up and let me watch my program?”

“Program? You talk like King Fluffybuns.” Sans laughs. He twists his body and scoots back so he can watch whatever Error decides to put on too. 

He skips through AUs and Sans watches with fascination. “This feels like an invasion of privacy.” Sans points out, but he doesn’t tear his eyes away from the screen. 

“Anomalies have no privacy.” He wonders how SFW Underlust is tonight. Sometimes, past the porn, there’s really good scenes. It’s almost as dramatic as Undernovela. 

“...Have you ever watched me?” 

“No.” Undertale is one of the only worlds he doesn’t have access too. Some of the more heavily protected AUs, like the original Underfell and Underswap, are harder to watch too. Error doesn’t think he would watch it even if he could, because the main universe makes him irrationally upset. Why would he purposely antagonize himself like that? 

“Good to know.” 

They lapse into another awkward silence. On the screen, an Aaron is dramatically breaking up with a Temmie. If fate is destined to repeat itself, Aaron is going to come running right back to her. This is probably the third time he’s called things off with her. Error doesn’t know why Temmie keeps taking him back. If it were him, he would laugh at the idiot before killing him. 

...Perhaps Sans’ statement on his violence holds  _ some  _ merit. Error would rather not think about it. 

“Aarons are always dicks, I see.” 

Error nods.

“And Temmies are always kind of dumb. That’s hilarious.”

“Eh, Underswap Temmie replaces your Flowey so I wouldn’t say  _ all  _ of them.” Although, Floweys aren’t really the brightest either. “Horrid abominations..”

“...How does Temmie replacing Flowey work?”

He shrugs. “Fuck if I know.”

True to Underlust nature, there’s a sex scene. Error huffs. It’s not even a good sex scene either. Porn with Aaron sucks. Although, It’s not as if Error actually  _ wants  _ to watch porn. He hasn’t had sex since before he became Error, (that one fumble with Ink most certainly not counting) so all porn ever does is make him feel...weird. 

If he’s being honest with himself, he misses being able to be touched. Error flexes his fingers before deciding that he’s had enough. Abruptly, the screen switches from Temmie blowing Aaron to some obscure AU where everyone is a magical girl. Another guilty pleasure of his. Not even he can resist the charming allure of this genre, abominations be damned. 

“Welp.” Sans says. “I think I prefer the porn.”

“Disgusting.” He’s as annoying as Ink, in his own right. There’s a reason why Error has made a conscious decision to stay away from the Main Universe at all times. 

“Aww. Porn is fun.”

“And magical anime girls  _ aren't?”  _

“Eh, more of Alphys’ thing to be honest. You don’t like porn?”

“Not when there’s other people watching with me!” He casts Sans a scalding look. Sans, who is most likely used to those kinds of expressions, grins lazily at him. 

“But aren’t we the same person?” 

“The only thing we share is bone structure.” He hisses. “What are you, a pervert? There’s no way in hell I’d watch porn  _ anyone _ .” 

Sans laughs. “But it’s not a big deal. Porn is a great stress relief. Beats dusting entire universes, you know.”

Is...is he telling him to masturbate instead of exterminate useless worlds? Like that would do any good! “Insufferable.”

And then... _ another _ sex scene? This time it’s between Undyne and Alphys, and from the looks of it, things are going pretty intense. What is with the multiverse today? It seems as if it does nothing but taunt him and lead him into unfortunate situations. He hates this. He wishes he didn’t even exist, so that he wouldn’t have to deal with this any longer. 

“Heh.”

This is it. This is his breaking point. 

“I’ve actually had enough this time for real.” He turns away from the screen. “You’re going home and-  _ woah holy shit what the fuck are you doing?”  _

Error chokes. 

Sans is leaned back with his legs spread. Inside of his shorts is his hand, which moves suspiciously underneath the clothing. Error’s jaw drops at the sight. How does he react to this? What is he supposed to do? He watches as Sans continues to fondle himself right in front of Error. 

“Enjoying the show.” His smile has a teasing edge to it. It sends little sparks to Error’s pelvic bone. Traitorous body. 

“Have you no shame!”

A faint blue glow illuminates his clothing. He’s summoned his ecto-body already? That’s even more scandalous! Which means that Sans isn’t touching bare bone, he’s...he’s...Error buries his head in his hands. His face feels like it’s on fire. 

“Like I said, we’re the same person. It doesn’t matter.” Sans twitches, his relaxed facade breaking for just a moment. “Cute. You even blush the same color as me. Same person, like I said.”

“Asjshdkj,” Error says. He has no other response. 

“Did you just keyboard smash out loud? I’ve never heard that before. That’s so cool.” His voice is strained. Error’s eyelights don’t leave his form. He’s enraptured by what’s happening in front of him, disgust slowly bleeding away into curiosity the more Sans pleasures himself. 

He finds that he wants to see what’s underneath those shorts. Is he playing with his clit? Or maybe he’s rubbing his dick. Either way, the movements become vigorous and energetic. 

“Hey.” Sans grunts out, his hand coming to a sudden halt. “If you show me yours I’ll show you mine.” 

Error’s eyes snap back to Sans’ face. Caught red handed. “What makes you think I want to see?” He growls. 

But, well. His body has made his arousal no secret, taking the opportunity to form itself without his permission. His cunt drips, leaving a dark stain in his pants. 

“No need to be shy. ‘S not like we’re being watched.”

That’s a lie. Someone is always watching. In this life, there is no such thing as privacy. Every movement they make is recorded. They’re creations, not people. Everything is fabricated, and right now this situation is probably the happenings of a cruel being wanting to see Error be put in an uncomfortable situation. 

But...Sans makes it easy to forget that he’s a thing and not a person. A contrast to Ink’s existence, which serves as a constant reminder. 

“I’m not shy.” He’s just more modest. Sans waits expectantly, and with a heavy flush Error shifts until his pants have been pulled off him. His thighs contrast sharply with the charcoal black of his bones, the blue of his ecto-body causing them to stand out more than before. He hates it. He hates his body, and the discoloration of his bones. Hates it, hates it-

Sans makes an appreciative sound. Error flinches and witnesses Sans lift his hips up to pull his own shorts off. It looks like he had the same idea as Error’s body, because in between his legs is a brightly glowing cunt. His fingers go right back to his pussy, and this time he can hear the soft squelch of his digits rubbing slick folds. 

“Even your body is the same.” Sans laughs breathlessly. “Same pussy. Isn’t that something?” 

“We’re nothing alike!” He spits. “Stop saying we are!”

“You’re right, we aren’t. But It’s nice to pretend that you’re somewhat normal, isn’t it?” 

God. He never shuts up. And he’s such an asshole when he speaks too. Ink and Fresh can excuse their asshole tendencies through their sheer stupidity, but Sans? He’s well aware of how cruel his simple words can be. Gaster taught him how to sharpen his tongue, and how to cut down people with his voice alone. Not even Nightmare is as effective as Sans. The son of a bitch could probably have the entire multiverse at his feet before his lunch break. 

After all, copies can never compare to the original. 

Error grits his teeth.

“I hate you.”

Sans smiles. He slips a finger inside of himself and pumps it leisurely. Error watches it disappear and then reappear through the flesh of his ecto-body. The white is barely visible, but Error can see it twist inside. Another finger joins it, and he begins to scissor his cunt. Error can’t stand how much that sight turns him on. 

“Hate is such a strong word.” 

“You always have a contradiction to what I say.” 

Sans shrugs. “I wouldn’t say always. We’ve only known each other for like, half an hour.” 

“That’s  _ another  _ contradiction.” 

He chuckles. Soft and genuine. “Sorry. I’m doing an awful lot of work here, why don’t you return the favor?” 

Error sighs. He spreads his legs and hesitantly touches himself at the area right above his clitoral hood. Massaging it always feels wonderful. It makes his whole pussy ache for something, which in turn makes him feel less like a touch-phobic freak and more like an actual person. 

(And now he’s contradicting himself. Didn’t he say earlier that he’s not a person but a thing?)

“Your pussy is kinda cute, you know.” Sans murmurs. His fingers pump in and out feverishly. “I’d eat you so good.”

He trembles at the thought of a mouth on his cunt. His other hand dips past the one playing with his pussy, and instead this one prods at his entrance. The wet sounds of Sans’ pussy drives him forward, boosting his confidence. 

“Oh? You like the thought of that?”

Error whines. Yes, he really does. 

“I’d get you nice and wet for me. Your pussy would be  _ soaked  _ by the end of it.” His finger breeches his entrance. It stings slightly; he hasn't masturbated in a long time. “You’d taste fucking awesome. I’d drink every last bit of your cum, and even after you're done cumming I’d keep going.” 

Filthy! Disgusting! Error’s pussy gushes uncontrollably. He’s being so talkative right now. Is that even in character for Sans? It feels like a script is being broken, but he’s not sure how. Regardless, his thoughts are too preoccupied by the way his stomach is clenching and unclenching. 

“Oh, oh, fuck. I’m-” A long groan cuts Sans off. Juices squirt from his pussy, coating his fingers and making a mess on the floor. The way he throws his head back and spreads his legs even further makes Error moan. 

Jesus, he’s so close. He opens his mouth in a silent scream, the stimulation bordering on too much. Just a few more clumsy thrusts and his own juices join Sans’ on the floor. He’s pussy clenches down tight around his finger, sucking him deep inside his own body. All the way to the knuckle. 

“That was fun.” Sans says weakly.

And. Well. Even Error can admit that it wasn’t the worst. 

**Author's Note:**

> Twitter is @ Snasational


End file.
